Characteristics Of Particulate Matter In An H-type Cage Layer House

Environmental pollution inside animal feeding operation（AFO）is becoming a big concern nowadays with the continuous expansion and mechanization development of layer farming.As one of the main air pollutants,Particulate Matter（PM）inside the layer house may pose adverse health effects to people and animals and limit the sustainable development of layer farming.This study was conducted to characterize the PM pollution in a commercial H-type high-rise layer house in Ningbo city,Zhejiang Province in winter,2019.The temperal and spatial variations and size distribution of PM were analyzed by the 10-point monitoring of temperature,relative humidity,PM_2.5 and PM₁₀.Concentrations and size distributions of water-soluble ions,organic/elemental carbon（OC/EC）and heavy metals,as well as concentrations and diversity of bioaerosols in the middle and rare of the house were analyzed by the Anderson 8-stage viable sampling of PM₁₀ and Anderson 6-stage viable sampling of cultivable Gram-negative bacteria.The main results are summarized as follows:（1）The mean daily PM_2.5 and PM₁₀mass concentrations were 107.2±13.4μg/m³ and513.0±213.8μg/m³（mean±SD）,respectively.The concentrations of PM were the highest at6:00-7:00 in the morning and at 17:00 in the afternoon and lowest at night.The concentrations of PM in the middle and rear of the house and in the upper rank were higher,which were related to temperature and relative humidity,as well as to the lighting and animal activity level.（2）The 8-stage PM₁₀sampling showed the PM was mainly distributed in the coarse particle mode.The concentrations of water-soluble ions in PM_2.1 and PM₁₀ were from 17.19±0.88μg/m³to 18.37±2.51μg/m³ and from 56.86±3.63μg/m³ to 67.67±11.89μg/m³,respectively,with Na⁺and PO₄^3-as the main components.The ion balance calculation showed that the coarse and fine particles were alkaline.OC/EC accounted for 14.54～17.25%and 43.18～42.64%of PM_2.1and PM₁₀,respectively.OC accounted for more than 90%of carbon fraction,indicating that organic matter was the main component of PM.It was estimated that the contribution rate of SOC to OC in PM₁₀ at the middle and rare of the house was 47.4%and 39.1%,respectively.Among the heavy metal elements,the proportions of Fe in PM_2.1 and PM₁₀were greater than50%,followed by Al and Zn,and the proportion of heavy metal elements at the middle of the house was higher than at the rare.（3）The 6-stage bioaerosol sampling showed the concentrations of cultivable gram-negative bacterial aerosols before,while and after manure cleanup were 0.351-0.704×10³ CFU/m³,2.764～2.883×10³ CFU/m³ and 2.104～2.544×10³CFU/m³,respectively.The proportions of inhalable microbial aerosols in the three stages of manure cleanup were 48.14%,22.07%and 36.41%,respectively.Pseudomonas,Escherichia-shigella and Comamonas were the dominant bacteria in genus level,and cultivable gram-negative microbial aerosols with particle size 1.1～2.1μm were the most abundant.Potential pathogenic bacteria such as Acinetobacter,Enterobacter,Escherichia and Pseudomonas were detected.This study provides more data for basic research on particulate matter in laying hens,and provides reference for health risk assessment of livestock and poultry farms.